Tuning Interfacial Properties by Spontaneously Generated Organic Interlayers in Top-Contact-Structured Organic Transistors

Abstract

Controlling the interfacial properties between the electrode and active layer in organic field-effect transistors (OFETs) can significantly affect their contact properties, resulting in improvements in device performance. However, it is difficult to apply to top-contact-structured OFETs (one of the most useful device structures) because of serious damage to the organic active layer by exposing solvent. Here, a spontaneously controlled approach is explored for optimizing the interface between the top-contacted source/drain electrode and the polymer active layer to improve the contact resistance (R-C). To achieve this goal, a small amount of interface-functionalizing species is blended with the p-type polymer semiconductor and functionalized at the interface region at once through a thermal process. TheR(C)values dramatically decrease after introduction of the interfacial functionalization to 15.9 k omega cm, compared to the 113.4 k omega cm for the pristine case. In addition, the average field-effect mobilities of the OFET devices increase more than three times, to a maximum value of 0.25 cm(2)V(-1)s(-1)compared to the pristine case (0.041 cm(2)V(-1)s(-1)), and the threshold voltages also converge to zero. This study overcomes all the shortcomings observed in the existing results related to controlling the interface of top-contact OFETs by solving the discomfort of the interface optimization process.